Microfabricated elastomeric valve and pump systems

Abstract

A method of fabricating an elastomeric structure, comprising: forming a first elastomeric layer on top of a first micromachined mold, the first micromachined mold having a first raised protrusion which forms a first recess extending along a bottom surface of the first elastomeric layer; forming a second elastomeric layer on top of a second micromachined mold, the second micromachined mold having a second raised protrusion which forms a second recess extending along a bottom surface of the second elastomeric layer; bonding the bottom surface of the second elastomeric layer onto a top surface of the first elastomeric layer such that a control channel forms in the second recess between the first and second elastomeric layers; and positioning the first elastomeric layer on top of a planar substrate such that a flow channel forms in the first recess between the first elastomeric layer and the planar substrate.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This nonprovisional patent application is a continuation-in-part of nonprovisional patent application Ser. No. 11 / 685,654, filed Mar. 13, 2007, which is a continuation of Ser. No. 11 / 056,451, filed Feb. 10, 2005, which is a continuation of Ser. No. 09 / 826,583, filed Apr. 6, 2001, which is a continuation-in-part of nonprovisional patent application Ser. No. 09 / 724,784, filed Nov. 28, 2000, which is a continuation-in-part of parent nonprovisional patent application Ser. No. 09 / 605,520, filed Jun. 27, 2000, which claims the benefit of the following previously filed provisional patent applications: U.S. provisional patent application No. 60 / 141,503 filed Jun. 28, 1999, U.S. provisional patent application No. 60 / 147,199 filed Aug. 3, 1999, and U.S. provisional patent application No. 60 / 186,856 filed Mar. 3, 2000. The text of these prior provisional patent applications is hereby incorporated by reference.STATEMENT AS TO RIGHTS TO INVENTIONS MAD...

AI Technical Summary

Benefits of technology

[0009]Advantages of fabricating the present structures by binding together layers of soft elastomeric materials include the fact that the resulting devices are reduced by more than two orders of magnitude in size as compared to silicon-based devices. Further advantages of rapid prototyping, ease of fabrication, and biocompatability are also achieved.

[0014]An advantage of patterning moderate sized features (> / =10 microns) using a photoresist method is that a high resolution transparency film can be used as a contact mask. This allows a single researcher to design, print, pattern the mold, and create a new set of cast elastomer devices, typically all within 24 hours.

[0015]A further advantage of either above embodiment of the present invention is that due to its monolithic or integral nature, (i.e., all the layers are composed of the same material) is that interlayer adhesion failures and thermal stress problems are completely avoided.

[0016]Further advantages of the present invention's preferred use of a silicone rubber or elastomer such as RTV 615 manufactured by General Electric, is that it is transparent to visible light, making a multilayer optical trains possible, thereby allowing optical interrogation of various channels or chambers in the microfluidic device. As appropriately shaped elastomer layers can serve as lenses and optical elements, bonding of layers allows the creation of multilayer optical trains. In addition, GE RTV 615 elastomer is biocompatible. Being soft, closed valves form a good seal even if there are small particulates in the flow channel. Silicone rubber is also bio-compatible and inexpensive, especially when compared with a single crystal silicon.

[0019]Further advantages of the present pumps and valves are that their small size makes them fast and their softness contributes to making them durable. Moreover, as they close linearly with differential applied pressure, this linear relationship allows fluid metering and valve closing in spite of high back pressures.

[0027]In other optional preferred aspects, magnetic or conductive materials can be added to make layers of the elastomer magnetic or electrically conducting, thus enabling the creation of all elastomer electromagnetic devices.

Problems solved by technology

Unfortunately, each of these approaches suffers from its own limitations.

A limitation of the first approach of silicon-based micro-machining is that the stiffness of the semiconductor materials used necessitates high actuation forces, which in turn result in large and complex designs.

In fact, both bulk and surface micro-machining methods are limited by the stiffness of the materials used.

In addition, adhesion between various layers of the fabricated device is also a problem.

On the other hand, when surface micro-machining, thermal stresses between the various layers of the device limits the total device thickness, often to approximately 20 microns.

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